Present status of trichostrongyliasis in Iran.

Infection with species of Trichostrongylus is common among man and animals in most parts of Iran, and human infections with T. orientalis, T. colubriformis, T. vitrinus, T. axei, T. capricola, T. probolurus, T. skrjabini, and a possibly new, unnamed species have been reported. All are found in Isfahan, central Iran, where the overall prevalence is 67% and the predominant species are T. orientalis and T. colubriformis. Among 737 nomads migrating from the central parts to the south, 86% were found to be infected with one or more of five species (in order of frequency): T. colubriformis, T. orientalis, T. axei, T. capricola, and T. vitrinus. In Khuzestan, southwest Iran, human infections with T. orientalis, T. colubriformis, T. axei, and T. vitrinus with an overall prevalence of 71% have been reported. In the northern parts, along the Caspian Sea, the rate is 7% and the species found, in order of frequency, are T. colubriformis, T. axei, T. vitrinus, and T. orientalis. Trichostrongylus infections are also found in the northwest but are rarely seen in the northeast. In most areas females are more frequently and more heavily infected than are males. All species found in man, except the new, unnamed species, are also found in sheep, goats, cattle, and camels; the number of species found and the order of their frequency differ in various animals and in different areas. Infection in other mammals, such as hares (T. retortaeformis and T. orientalis) and porcupines (T. orientalis), has also been reported.